diff options
Diffstat (limited to 'common-algo.c')
| -rw-r--r-- | common-algo.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/common-algo.c b/common-algo.c index 5d5de01..a8d9669 100644 --- a/common-algo.c +++ b/common-algo.c @@ -25,6 +25,7 @@ #include "includes.h" #include "algo.h" +#include "session.h" #include "dbutil.h" #include "kex.h" #include "ltc_prng.h" @@ -257,6 +258,9 @@ algo_type sshkex[] = { #endif {"diffie-hellman-group1-sha1", 0, &kex_dh_group1, 1, NULL}, {"diffie-hellman-group14-sha1", 0, &kex_dh_group14, 1, NULL}, +#ifdef USE_KEXGUESS2 + {KEXGUESS2_ALGO_NAME, KEXGUESS2_ALGO_ID, NULL, 1, NULL}, +#endif {NULL, 0, NULL, 0, NULL} }; @@ -299,6 +303,122 @@ void buf_put_algolist(buffer * buf, algo_type localalgos[]) { buf_free(algolist); } +/* match the first algorithm in the comma-separated list in buf which is + * also in localalgos[], or return NULL on failure. + * (*goodguess) is set to 1 if the preferred client/server algos match, + * 0 otherwise. This is used for checking if the kexalgo/hostkeyalgos are + * guessed correctly */ +algo_type * buf_match_algo(buffer* buf, algo_type localalgos[], + enum kexguess2_used *kexguess2, int *goodguess) +{ + + unsigned char * algolist = NULL; + const unsigned char *remotenames[MAX_PROPOSED_ALGO], *localnames[MAX_PROPOSED_ALGO]; + unsigned int len; + unsigned int remotecount, localcount, clicount, servcount, i, j; + algo_type * ret = NULL; + const unsigned char **clinames, **servnames; + + if (goodguess) { + *goodguess = 0; + } + + /* get the comma-separated list from the buffer ie "algo1,algo2,algo3" */ + algolist = buf_getstring(buf, &len); + TRACE(("buf_match_algo: %s", algolist)) + if (len > MAX_PROPOSED_ALGO*(MAX_NAME_LEN+1)) { + goto out; + } + + /* remotenames will contain a list of the strings parsed out */ + /* We will have at least one string (even if it's just "") */ + remotenames[0] = algolist; + remotecount = 1; + for (i = 0; i < len; i++) { + if (algolist[i] == '\0') { + /* someone is trying something strange */ + goto out; + } + if (algolist[i] == ',') { + algolist[i] = '\0'; + remotenames[remotecount] = &algolist[i+1]; + remotecount++; + } + if (remotecount >= MAX_PROPOSED_ALGO) { + break; + } + } + if (kexguess2 && *kexguess2 == KEXGUESS2_LOOK) { + for (i = 0; i < remotecount; i++) + { + if (strcmp(remotenames[i], KEXGUESS2_ALGO_NAME) == 0) { + *kexguess2 = KEXGUESS2_YES; + break; + } + } + if (*kexguess2 == KEXGUESS2_LOOK) { + *kexguess2 = KEXGUESS2_NO; + } + } + + for (i = 0; localalgos[i].name != NULL; i++) { + if (localalgos[i].usable) { + localnames[i] = localalgos[i].name; + } else { + localnames[i] = NULL; + } + } + localcount = i; + + if (IS_DROPBEAR_SERVER) { + clinames = remotenames; + clicount = remotecount; + servnames = localnames; + servcount = localcount; + } else { + clinames = localnames; + clicount = localcount; + servnames = remotenames; + servcount = remotecount; + } + + /* iterate and find the first match */ + for (i = 0; i < clicount; i++) { + for (j = 0; j < servcount; j++) { + if (!(servnames[j] && clinames[i])) { + // unusable algos are NULL + continue; + } + if (strcmp(servnames[j], clinames[i]) == 0) { + /* set if it was a good guess */ + if (goodguess && kexguess2) { + if (*kexguess2 == KEXGUESS2_YES) { + if (i == 0) { + *goodguess = 1; + } + + } else { + if (i == 0 && j == 0) { + *goodguess = 1; + } + } + } + /* set the algo to return */ + if (IS_DROPBEAR_SERVER) { + ret = &localalgos[j]; + } else { + ret = &localalgos[i]; + } + goto out; + } + } + } + +out: + m_free(algolist); + return ret; +} + #ifdef DROPBEAR_NONE_CIPHER void |